1. Field
Methods and apparatuses consistent with exemplary embodiments described herein relate to a broadcast receiving device and method, and more particularly, to a broadcast receiving device and method which can be used to change channels quickly.
2. Description of the Related Art
Generally, digital broadcast receiving devices, such as digital televisions (TVs) and Internet protocol (IP) TVs, provide better image and sound quality than analog broadcast receiving devices. However, digital broadcasting receiving devices require a longer time to change from a currently selected channel to a channel requested by a user than analog broadcast receiving devices.
When a channel change command is received from a user while a broadcast signal of a selected channel is being displayed on the screen, the time required for a radio frequency (RF) tuner to tune to a channel requested by the user is all of the time that an analog broadcast receiving device needs to change to the requested channel.
By contrast, when a channel change command is received from a user while a broadcast signal of a selected channel is being displayed on the screen, a digital broadcast receiving device typically requires about one or two seconds more time than an analog broadcast receiving device to receive a broadcast signal of a channel requested by the user and to display the received broadcast signal on the screen. Specifically, the time required by the digital broadcast receiving device to change to the channel corresponding to the channel change command received from the user includes the time required for an RF tuner to tune to the requested channel, the time required until an intra (I) picture is received after the change to the requested channel, and the time required to buffer a predetermined number of frames in a group of pictures (GOP) that includes the received I picture.
A moving image that is compressed using digital image compression technology, such as, for example, Moving Picture Experts Group 2 (MPEG2) or H.264, typically consists of a plurality of groups of pictures (GOPs), each GOP including I, predictive (P), and bidirectionally predictive (B) pictures. A digital broadcast receiving device buffers such a moving image on a GOP-by-GOP basis. After buffering all frames (i.e., pictures) in a GOP, the digital broadcast receiving device decodes the frames in the GOP, so that the frames can be displayed on the screen.
While an image of a selected channel is being displayed, if channel change command information is received from a user, the digital broadcast receiving device enters a standby mode until it receives an I picture of a channel corresponding to the channel change command information received from the user. Then, the digital broadcasting receiving device buffers all frames in a GOP, including the received I picture. After buffering all frames in the GOP, the digital broadcast receiving device decodes the frames in the GOP and displays the decoded frames on the screen.
As described above, to change from a currently selected channel to another channel requested by a user, a digital broadcast receiving device requires the time that elapses until an I picture of the requested channel is received, plus the time that elapses while buffering all frames in a GOP including the I picture, plus the time that elapses while decoding the buffered frames so that the decoded frames can be displayed on the screen. Hence, the user experiences a delay, and therefore cannot watch a moving image of the requested channel more immediately.